Epidemiologic evidence has established that shift work exposure is associated with an array of adverse health consequences, including increased risk of cardiovascular disease, gastrointestinal disease, and cancer. Investigations of the mechanisms linking shift work and disease have highlighted the importance of nocturnal light exposure and the consequent chronic disruption of circadian organization. Recent evidence that light input to the circadian system is mediated by neural systems distinct, anatomically and functionally, from those involved in vision provides a theoretical foundation for addressing this pathophysiology in shift workers. Recent work has demonstrated that the use of filtering lenses to eliminate the deep blue end of the visual spectrum (< 480nm) normalizes endocrine and genetic indices of circadian organization and significantly improves nocturnal alertness and performance. The overall goal of this SBIR project is to develop spectrum-specific, indoor LED lighting solutions that provide usable indoor illumination absent the spectral components that are associated with circadian disruption. The development process will aim to achieve an optimum balance between protection of normal nocturnal physiology and color rendition by combining specially designed optical filters with the use of light sources that meet certain defined spectral requirements. Indoor lighting that could be used at night without producing circadian disruption, providing the potential for immediate improvements in alertness and performance and long-term improvements in shift worker health, would have significant potential application in the large and growing segment of the modern economy that requires night work. The development of this ZircLight lighting will be based on laboratory physiological testing, first with ZircLight prototypes based on specially selected commercially available light bulbs and custom-designed filters, and second with specially designed ceiling panels, based on LED chip arrays rather than light bulbs, which will be compatible with the common workplace lighting infrastructure. We intend to demonstrate the physiological effectiveness of these ZircLight ceiling panels in laboratory and workplace studies. This Phase II SBIR project will address three specific aims: 1) Refinement of spectral characteristics of ZircLight prototypes and testing of their physiological functionality in a laboratory shift work simulation; 2) Design and fabrication of test units of 2x2 ZircLight ceiling panels and testing of physiological functionality in a laboratory shiftwork simulation; 3) Evaluation of physiological effectiveness and operational functionality of ZircLight in shift work settings. The primary outcome measure for laboratory and workplace testing will be salivary melatonin, and secondary outcome parameters include salivary cortisol circadian gene expression, neurobehavioral parameters (alertness, performance, sleep, mood) and subjective light perception.